EVALUATION OF INFRARED TYMPANIC THERMOMETERS ON MILD HYPOTHERMIC SUBJECTS AND IN COLD ENVIRONMENTS

The objective of the present study was to evaluate infrared tympanic thermometers (ITTs) on hyothermic subjects and under operationally relevant ambient conditions. Eight subjects (2 of them female) were cooled in 8-10C water for 25 min on three occasions. Tympanic temperatures obtained with three bands of ITTs (Genius (TRADEMARK), Thermoscan (TRADEMARK), and Diatek (TRADEMARK)) were compared to three other core temperature estimates (esophageal, rectal, and ear canal) during the cold water immersions, and in a second series of experiments, to a temperature controlled target in cold air environments. On average, tympanic temperature (Tty) measured from the three ITT instruments was 0.99 + or - 0.18C lower than the other core estimates. The differences between Tty and each of the three core estimates were not different, but the three differences were larger for the Genius (TRADEMARK) ITT (1.49 + or - 0.36C) compared to the two other instruments (0.63 + or - 0.21C for Diatek (TRADEMARK); 0.63 + or - 0.20C for Thermoscan (TRADEMARK)). Furthermore, the ITT instruments failed to perform adequately in the cold. It was concluded that tympanic temperature measured by ITT instruments underestimates core temperature during hypothermia in humans, and the ITTs can not be used below their specified operating temperature.